Con. Ent. 108: 1303-1318 (1976) Bionomics of the stream caddisflies, Ceraclea transversa (Hagen) (= Athripsodes angustus Banks) and Ceraclea ancylus (Vorhies) (= Athripsodes ancylus (Vorhies)) were compared with generalized trichopteran life cycles. The univoltine detritus-feeding C . ancylus has five larval instars and a brief adult emergence period. C. transversa has five larval instars but two distinct cohorts, in which larvae of the first cohort feed entirely on freshwater sponge, overwinter as inactive prepupae, pupate, and emerge the following spring. The second larval cohort feeds on sponge until the onset of gemmulation in autumn, then the larvae must overwinter as active third-or fourth-instar detritus-feeders, pupating and emerging later in the summer than the first cohort. The detritus-feeding C. ancylus larvae have a diurnal feeding cycle. The sand case of C. ancylus and the silk-secreted case of C. transversa differ in shape and composition, although both species initiate case construction using egg mass matrix, silk, and detritus. Emergence, flight activity, sex ratios, and adult survival depart from reported generalizations of caddisfly biology. Neither the validity of generalizing typical life cycles in benthic studies, nor the rationale that congeneric species operate as a functional unit in stream dynamics, is substantiated.Leptoceridae, in studies that rely only on benthic sampling. The single generic designation is misleading as the two species represent distinct and diverse branches of the caddisfly genus Ceraclea that differ both morphologically and ecologically. MethodsThe life histories of C . ancylus and C . transversa were studied in Brashears Creek, a stream in the Salt River drainage, Spencer Co., Kentucky, during 1970-1973 Creek is characterized by high hardness and alkalinity, and exhibited the following ranges of selected water chemistry parameters (in ppm): -NO,: 0.04-4.9; -NOz: 0.01-0.04; -PO4: 0.32-0.46; -SO4: 20-56; Ca: 33-86; hardness: 130-280; alkalinity: 79-212; and conductivity: 200-460 ohms. Biological and chemical features of the stream are fully described by Krumholz (1971), Krumholz andNeff (1972), and Krumholz (1973).Immature and adult stages of both species were collected using quantitative and qualitative techniques. Eggs for laboratory rearings were obtained by the method reported by Resh (1972). Larvae and pupae were collected quantitatively using a Surber sampler at monthly intervals over several annual cycles. These collections were supplemented by qualitative collections often taken as frequently as weekly. Since part of the life cycle of C. transversa is linked to the fresh-water sponge, samples of Spongilla lacustris (L.) were collected biweekly from May through November (1970)(1971)(1972)(1973). An attempt was also made to quantify these collections on a relative basis by standardizing the length of collection time, and recording the volume of sponge collected. Adults were collected according to a light trap sampling regime described in .Instar determinatio...

Nymphal stages of Melanoplus bivittatus (Say) and M. femurrubrum (DeGeer) that were reared on five plant diets fed and grew at different rates. Differential mortality was obtained among the two species reared on the various diets, with the highest occurring in those feeding on alfalfa. On all plants a direct linear relationship was obtained between rate of food consumption and rate of growth, and slopes varied from 0.18 to 0.25 in M. bivittatus and from 0.14 to 0.18 in M. femurrubrum. The approximate digestibility on the various plants were all in the range of 41 to 47% for M. bivittatus and 37 to 48% for M. femurrubrum. The efficiency of conversion of digested food to body tissue (ECD) varied from 35 to 44% in M. bivittatus and from 33 to 44% in M. femurrubrum. The efficiency of conversion of ingested food to body tissue (ECI) varied from 15 to 18% in M. bivittatus, and from 15 to 19% in M. femurrubrum. Egg production in M. bivittatus varied from 196 on corn to 450 on radish; it was lower in M. femurrubrum, and varied from 162 on corn to 336 on the mixed diet.

The bioenergetics of annual populations of the dusky grasshopper, Encoptolophus sordidus costalis, on a natural grassland site were examined. Peak dry weight biomass of these insects reached 1.7 kg/ha (1.85 lb/at). Oxygen consumption ranged from 2.76 μl/h for first instar nymphs to 82 μl/h for adults, values that equated with an average consumption of 341 ml oxygen/m2 during the growing season. Energy values (cal/mg) of insect body tissue averaged 5.24 while those for exuviae, faeces, and plant material were 5.38, 4.08, and 4.39, respectively. The grasshoppers ingested 2% of the green shoot primary production, which, at the latitude of the Matador experimental site, was equal to 792 kcal/m2 in 1968–69. An additional 8% was cut and dropped so that a total of 10% of the green vegetation was removed by this insect species. Twenty-five percent of the ingested food was metabolized; the rest was voided as faeces. Respiration accounted for 51% of the metabolized energy. Exuviae made up 6 to 11% of secondary production. Ninety-seven percent of the potential energy of the green vegetation removed by the grasshoppers was returned to the "decomposer compartment" of the ecosystem, with only 3% removed or lost from the system.

Differential survival and development rates were obtained for the bertha armyworm, Mamestra configurata Wlk., reared at nine constant temperatures. Eggs and larvae had high survival rates at temperatures ranging from 8 °C to 32 °C and pupae showed good survival between 8 °C and 28 °C. Eggs and larvae did not complete development at 6° and 36 °C; and 32 °C was lethal for pupae. Duration of the egg, larval, and pupal stages decreased as the temperature increased from 8 °C to 28 °C. When duration and developmental rates were plotted against temperatures, the observed points did not differ significantly from curves formulated from the logistic equation 1/y = K/(1 + ea−bx). With a developmental threshold of 7 °C, 82, 356, and 352 accumulated day-degrees above the threshold were required for development of eggs, larvae, and pupae, respectively.

The feeding habits of Melanoplus bivittatus (Say) and M. femurrubrum (DeGeer) in an Ontario grassland were investigated by analyzing crop contents. The study revealed that both species are mixed feeders which prefer forbs over grasses. Both species ingested a wide range of host plants in the field, showing preferences for some species over others. Differential growth and mortality resulted when grasshoppers were reared on different host plants.